Telephone system.



A. H. DYSON & F. W. DUNBAR.

TELEPHONE SYSTEM.

APPLICATION FILED JUNE 21,1906.

Patented Dec. 22, 1908.

3 BHBETB-SHBBT 1.

IHVEHTORSIM A. H. DYSON & P. W. DUNBAR.

TELEPHONE SYSTEM.

APPLICATION FILED mun 21, 1905.

Patented Dec. 22, 1908.

3 SHEBTS-SHEET 2.

.E. WE w ill m. x 4/ 7 m %m w Z A. H. DYSON & F. W. DUNBAR.

TELEPHONE SYSTEM.

APPLICATION IILED mm: 21, 1005.

907,582, Patented Dec. 22, 1908.

3 SHEETS-SHEET 3.

IIHIIIIIIII lllllnlam munlum lV/YYVESSES: INVENTOMS,

UNITED STATES PATENT- OFFICE.

ALFRED H. DYSON AND FRANCIS W. DUNBAR, OF CHICAGO, ILLINOIS.

TELEPHONE sYs'rnM.

Specification of Letters Patent.

Patented Dec. 22, 1908.

Application filed June 21, 1905. Serial 1 70. 266,281.

I a system of the described character, in which a central source of current is used for the double purpose of operating the switches and supplying current for conversational purposes. It is common practice in systems of this character to efi'ect the release of the automatic switches, used in an established connection, by causing a subscriber to simultaneously ground the two limbs of his telephone line at the substation, this act operating to throw out of balance the windings of a diil'erential relay at the exchange, whereby the core of the relay becomes magnetized and attracts an armature to close circuit through the apparatus provided for returning the said switches to normal.

In accordance with the common practice mentioned, we provide a differential relay for the purpose, but arrange its windings in such manner that, in addition to the function above mentioned, it also acts during conversation as a repeating device, inductively uniting the conversational circuits of the two connected substations. Such a relay may be called a differential repeating relay.

Referring to the drawings, Figure 1, consisting of sheets 1 and 2, illustrates diagrammatically two telephone lines extending from substations to the exchange and apparatus at the exchange suitable for uniting them in a conversational circuit. In Fig. 2 is shown a eneral view of a selective switch mechanism or use in connection with the circuits of Fig. 1. 3 is a top view oi the primary magnot of the said switch and its parts. Fig. wL

shows a side view of the primary magnet in, pavzl and shaft ratchet. ,Fig. 5

cluding the is a perspective view of the side switch parts. Fig. 6 is a top view of the secondary magnet, its pawl and. the associated shalt ratchet. Figs. 7 and 8 show respectively top and front views of the bank contacts of the switch.

Referring to Fig. 1, at A, we have illus Hated, diagrammatically, substation apparatus including the usual transmitter, hook switch, receiver, induction coil, condenser and bell. We provide, in addition there i, a calling device 1 and a releasing device, consisting of springs 8, 9 and 10, adapted to be operated by arm 6" forming art of the hook lever. P and S are the two limbs of the telephone line extending to the exchange and there connected with the circuits of first selector switch B, which, in the system shown, is individual to the line of subscriber A. This switch may comprise shaft 43, wipers 44, 45 and 46 attached thereto, and multipled terminals of a plurality of second selector switches adapted to be engaged by the said wipers. The terminals of the latter switches may conveniently be arranged in groups, the switches of each group being as signed for connection to a division of one thousand subscribers lines. The circuits illustrated atB include means, controllable from substation A by means of calling device 1, adapted to effect primary movements. of shaft 43 to cause it to move wipers 44, 45 and 46 to positions adjacent to, but not engaging, terminals of the second selector switches of any group. It also provides means, rcsponsive to calling device 1, for initiating secondary movements of shaft 43 to cause the wipers to move over the terminals of a selected group of second selector switches, their motion being arrested when they engage terminals of an idle switch. Second selector switch C may comprise shaft 84 and wipers 85, S6 and 87 attached thereto and terminals of connector switches adapted to be engaged by the said wipers. These terminals may be arranged in groups, the connector switches 01 each group being assigns a diilerent one hundred-line division of the one thousand-line division to which the second selector switch is rssigned. The second selector switch comprises means, adapted to be operated from the substation let A, when the line at the substation is connected through to the switch, by calling device 1, for imparting primary movements to shaft 84 to cause the wipers of the second selector switch to move to positions adjacent to the difiercnt groups of terminals of thc conncctor switches described. Means arc also provided, rcsponsive to calling device 1, for imparting seconitfor connection to when they engage terminals of an idle con- 1 to the left of spring 8. He thereupon renect r switch. A connector switch, such as i we he: a illustrated at D, may include a shaft lines adapted to be engaged by the wipers. The said terminals may conveniently be arranged in ten groups of ten each, the first group including lines numbered from 1 to 10; the second, lines numbered from 1 1 to 20; the third, lines numbered from 21 to 30, etc. of the one hundred to which the particular connector switch is assigned. The con nector switch may also include means controllable from a substation, as A, by means of calling device 1 when the line at the substation is connected through to the connector switch, for imparting primary movements to the shaft to bring the wi ers adjacent to, but not engaging, any one o the aforementioned ten groups of line terminals. It further provides means, responsive to calling device 1,

adapted to impart secondary movements to the shaft to cause the wi ers to move into engagement with termina of any line of a selected ten line group. The connector switch provides means whereby the callin subscriber may cause the bell of the calle subscriber to ring. it further includes means for supplying talking current from a central source to the transmitters of connected subscribers, and a difl'erential repeating relay such as we have before described.

An exchange, provided with switches of the three classes mentioned, may be used to supply service to several thousand subscribers. Second selector switches and connector switches may be much less numerous than first selector switches (which, before stated, are individual to subscribers lines), the system operating on the multiple trunking principle, well known in the art.

'1 1e mechanical connections between the shafts of the various switches and the electromagnets operating them, the arrangements of the terminals engaged by the wipers of the various switches and the me chanical forms of switches generally, may be of any approved character. Our invention does not require any articular arrangement of these mcchanica parts, but consists rather in certain features of the circuit arrangement illustrated.

having described our invention in a eneral way, the detailed relation to the di erent parts of the circuits, shown in Fig. 1, to one another may best be understood from a narrative of operation of the system. Assuming that subscriber A desires to be con nected with subscriber F, whose number is assumed to be 2342, subscriber A effects switching movements as follows: He first removes his receiver from the switch hook, which act operates to close contact 67 and to move arm 6. attached'to the hook lever.

volves calling device 1 in the direction indi- 3 cated by the arrow, until two teeth of the 154 with wipers 148, 149 and 150 and multipled terminals of one hundred subscribers ratchet shown thereon pass beneath spring 2. lhe revolution of the dial at its start brings the pin, shown upon, the dial, to disengage the spring with which it is shown engaged, which by its tension disengages its associated contact spring, thereby opening circuit through the substation transmitter and conductively disuniting limbs P and S. 'lhese springs remain disengaged until the calling device returns to normal. Having moved two teeth below spring 2, subscriber A releases the calling device which thereupon revolves in the opposite direction, closing and opening contact, by the engagement of its teeth with spring 2, between springs 2 and two times. Two impulses of current thereu on flow'irom ground at the substation, t rough contact 3-2 to limb I of the line, over the said limb to the exchange, throu h contact 3233 of first selector switch through the winding of relay 12 to the active side of grounded battery 22,.causing two energizations and denergizations of the said relay and two attractions and releases of its armature. Two impulses of current are thereby caused to flow from ground at the first selector switch, through contact 1413, through armature 19, through the winding of primary magnet 17 to battery 22. Two energizations of the said rimary magnet are caused thereby, the sai magnet imparting motion to shaft 43, such that wipers 44, 45 and 46 are moved to positions adjacent to terminals of a group of second selector switches assigned to a division of subscribers lines, including numbers .from 2000 to 2999. As soon as shaft 43 moves, contact 4242* is closed, placing ground on terminal 151 and its multiples, which thereupon test busy to connector switches having access to them.

Referring again to substation A, it will be noted that calling device 1, after effecting the second closure of contact between springs 2 and 3, causes contact between springs 5 and 4 to be made and broken a single time in its return to its normal position illustrated. An im ulse of current thereupon flows from groun at the substation,-through contact 5*4, to limb S of the line, over the said limb to the exchange, through contact 36-37, through the winding of relay 16 to battery 22. The consequent attraction and release of the relays armature establishes a path for the flow of current from ground at the first selector switch, through contact 14-15, through the winding of relay 18 to battery 22. .The resulting energization and denergization of relay 18 moves arms 24, 28, 32

tery 22. The engagement of arm 24 with contact point 26 closes circuit through secondary magnet 21 which thereupon attracts its armature and imparts a secondary movement to shaft 43 in such manner that wipers 44, 45 and 46 engage the terminals of the first second selector switch of the before mentioned group. In case this second selector switch is idle, the deenergization of secondary magnet 21, which ensues immediately upon its energization, due to the vibratory character of its circuit, operates to move arms 24, 28, 32 and 36 into engagement with contact points 27, 31, and 39, respectively.

In case the second selector switch is already in use, the engagement of wiper 44 of first selector switch B" with contact terminal 47 of the first second selector switch of the group establishes a circuit, causing a second encr gization of relay 18 01 the first selector switch of subscriber A as follows: from ound at the first selector switch then renering the second selector switch busy, through contact 3128 of said first selector switch, through relay 40 to wiper 44 of the said first selector switch, to a multiple of the terminal engaged by wiper 44 of the first selector switch of subscriber A, to the terminal engaged, to wiper 44 (Fig. 1), through the windlng of relay 40, through contact 28-30 and through the winding of relay 18 to the active side of battery 22. The windings of relays 40 are so proportioned to that of relay 18 that this flow of current is insufficient to cause the attractions of their armatures. The energization of relay 18 operates to prevent movement of arms 24, 28, etc. to engage contact points 27, 31, etc. upon the deenergization of secondary magnet 2 1. Owing to the fact that contact 2426 thus remains closed, magnet 21 is energized and deenen;

circuit is continued through. relay 18 unbroken, the relay continuing to prevent the movement of arms 24, 28, etc; Secondary magnet,21 continues to vibrate, imparting successive secondary movements to shatt '43, which move wipers 44, 45 and 46 into engagement with terminals of successive sec-. H

fselgctor switch C, through contact 56-57, through the winding ofrelay 61. to batv0nd selector switches of the group, until terminals of an idle switch are engaged.

case, no first selector switch is connected ton multiple of terminal 47 of such second selector switch; the circuit through rel 1y 18 is broken, and the relay denergized, which then allows the retraction of the armature of secondary magnet 21 to move arms 24. 28, 32 and 36 into engagement with contact points 27, 31, 35 and 39. respectively. 'Wipg'ns 44, 45 and 46 are now in engagement with terminals 47, 48 and 49 of idle second selector switch C, terminal 47 of the second selector switch rendering its multiples busy, due to the closing of contact 2831, thus preventing intrusion from other first selector switches having access to switch C.

The closure of contacts 32-35 and 36-39, as above described, extendsthe circuits of limbs P and S of the telephone line of subscriber A through to wipers 45 and 46 and to the circuits of second selector switch U, rendering it controllable from substation A. Subscriber A now revolves calling device 1 until three teeth have passed below spring 2, and releases it, the device in its return to normal closing and breaking contact three times between springs 2 and 3. Three imulses of current are thereby caused to flow rom ground at the substation, through contact 3-2 to limb P of the telephone line, over the said limb, through contact 32-35, contact 4548, contact 76-7 7 through the winding of relay 51 to the active side of battery 22, causing three energizations and deenergizations of the said relay. Three resulting attractions and releases of the relays armature cause three impulses of current to flow from ground at second selector switch 7 0, through contact 56 55, through armatrue 62, throughthe Winding of primary magnet 60 to battery 22, causing three energizations and denergizations of said magnet. The said magnet operates to im art three primary movements to shafit 84, w ich moves wi ers and 87 to positions adjacent to,, ut not engaging, multipled terminals of agroup of connector SWltOllQS assigned for connection to' a division of subscribers lines including numbers from 300 to 399 of the second one thousand division, or from 2300 to 2399.

Referring again to substation A, calling device 1, as it reaches normal, closes and breaks contact a single time between springs 5 and .4, causing an impulse to flow from ground at the substation, through contact 54, to limb S of the telephone line, over the said limb, through contact 36-39, contact 46- 49, contact 8081, through the winding of relay 59 to battery 22, which causes the-energization and denergization of the said relay. The resulting attraction and release of its armature causes an impulse of currentto flow from ground at second tery 22, causing the en'ergization and deenergization of the said relay. This operates to move arms 68, 72, 76 and 80 into en agement with contact points 70,74, 78 an 82,

.res ectively, The ergagement of arm 68 wit contact point 70 causes secondary magnet 63 to become energized, its denergization immediately following, due to the vi iratory character of its circuit. The energization of the said magnet operates to impart a second- .61 to battery 22.

ary movement to shaft 84, such that wipers 85, 86 and 87 are moved into engagement with terminals ol the ilrst connector switch of the bei'ore mentioned groupl Should this he an idle switch, the rlenergization of magnet 63 and the consequent retraction of its armature operates to move arms 68, 72, 76 and 80 into engagement with contact points 71, 75, 7t) and 8 3. respectively, the closing of contact 68-71 preventing further energization oi' magnet 63, and the closing of contact 75-72 putting ground upon the multiples or the terminal of the connector switch engaged by wiper 85, rendering the said switch busy. Should, however, the first connector switch be busy, upon the engagement of wiper- 85 with its terminal 88, circuit is closed through relay 61 of second selector switch 0 as follows: from ground at the second selector switch then connected with the said connector switch, through contact 75-72, relay 65 to wiper 85 ofthe second selector switch rendering the connector switch busy, to a multi le of the terminal engaged by wiper 85 0 second selector switch C, to the terminal en aged by wiper 85, through relay 65 of secon selector switch C, through contact 72-74 and through the winding of relay The windings of relays 65 are so proportioned to that of relay 61 that this flow of current is insufiicient to cause the attractions of their armatures. The energization of relay 61 prevents the movement of arms 68, 72, etc. to engage contact points I 71, 75, etc. upon the retraction of the armature of secondary magnet 63. Arm 68 therefore remaining in engagement with contact oint 70, magnet 63 is alternately energize and deenergized, each time causing a secondary movement of shaft 84 which moves wipers 85, 86 and 87 to engagement with terminals of successive connector switches, until terminals of an idle one are reached. When this occurs, circuit through relay 61 is broken, the relay is denergized and the retraction of the armature of magnet 63 now operates to move arms 68, 72, 76 and 80 into en agement with contact points 71, 75, 79 an 83, respectively. Arm 68 disengaging contact point 70, further energization of magnet 63 is prevented and wipers 85,86 and 87 rest in engagement with terminals 88, 89 and 90 of idle connector switch D. -The engagement of arm 72 with contact point 75 places ground, through relay 65, upon terminal 88 and its multiples, rendering the connector switch busy with respect to other second selector switches having access to it. The closing of contacts 76-79 and 80-83 1 extends the circuits of limbs P and S throu h to wipers 86 and 87 and through them to t e circuits of the connector switch selected, rendering it controllable from substation A by calling device 1.

Subscriber A now operates the calling device to send four impulses of current over limb P of the line, the said lmpulses assln through contact 86-89, switch C, t irougi the winding of relay 91 of the connector F switch, to the active side of roundedbattery 98. Four energizations an deenergizations of the relay are effected thereby, the resulting attractions and releases of its armature causing four impulses of current to flow from ground at the connector switch, through contact 94-93, through contact 100-101, through contact 129-130, through the winding of primary magnet 125 to the active side i of grounded battery 126. Four energizetions of primary magnet 125, caused thereby, effect four primary movements of shaft 154, which moves wipers 148, 149 and 150 to positions adjacent to, but not engaging, terminals of a group of lines including those numbered from 2341 to 2349 inclusive, followed by terminals of line 2340.

Referring to substation A, the return of dial 1 causes a single impulse to flow from ground at thesubstation, through contact 5-4, over limb S of the line, through contact 87-90, switch C, through contact 105- 108, through the winding of relay 97 to battery 98, causing the relay to be energized and denergized. The attraction and release of its armature causes an impulse of current to flow from ground at the connector switch, through contact 94-95, through the winding of relay 99 to battery 98. The resulting energization and denergization of relay 99 operates to cause arms 129, 133, 139 and 143 to engage, respectively, contact points 131, 135, 141 and 145. Subscriber A now operates calling device 1 to send two im ulses of current from ground at the su station, throu h contact 3-2, over limb P of the line, t rough the Winding of relay 91 to battery 98. The resulting attractions and releases of the relays armature cause two impulses of current to flow from ground at the connector switch, through contact 94-93, contact 100101, contact 129-131, through the winding of secondary magnet 128 to battery 126. Secondary magnet 128 is twice energized and denergized, effecting two secondary movements of shaft 154 which moves wipers 148, 149 and 150 into engagement with terminals of the second subscribers line of the before mentioned group, or of line #2342 of the called-for subscriber, whose substation is assumed to be F. The return of the calling device of subscriber A to normal causes an impulse of current to flow from ground at the substation, through relay 97 of connector switch D, causing the relay to attract its armature and, as before described, thereby cause the energization of relay 99. Assuming the line of subscriber F to be already in use or busy, the attraction of armature 102 to engage anvil 103, upon the energization of relay 99, causes current to flow from ground. through contact 151--148,

through contact 133-135, through contact ]O3-102, through the winding of release magnet 122 to battery 98. When'relay 99 5 is deenergized. upon the cessation of-the impulse, contact 1U3102 is opened and reease magnet 122 is denergized, causing the retu n of shaft 154 and its wipers, together witli arms 129, 133, 139 and 143, to normal. The ground connection to terminal 151 may be established in either of the following ways. Should subscriber F, at the time connection is made with his line, he a calling subscriber the first primary movement of the shaft oi his first selector switch E allowed spring 42 to engage anvil 42, thus placing ground, through the said contact 42---42, upon terminal 151. Should another subscrlber already have established connection with the 20 .line of subscriber F, terminal 151 is connected to ground at the connector switch already connected with a multiple of the said terminal, through contact 133-136 of the said connector switch. Subscriber A now depresses key 11, grounding limb P of the line at his substation, this being the switchin operation for rin ing the bell of the caller subscriber, shoul his line be idle. Under the circumstances described, however, the connector switch having been released and returned to normal, this grounding of limb P of the line of subscriber A causes the energi zation of relay 91 of the connector switch which, in turn, causes the energization of primary magnet 125, which. im arts a primary movement to shaft 154. l he first primary movement of the said shaft, which may be in a vertical direction, causes lug 147 to move spring 137 into engagement with anvil 138. The closing of contact 137 138 causes, in the subscribers receiver, the characteristic busy signal from busv back machine 127, circuit being traced tirough contact 137--138, contact 111 109, over the talking circuit at the exchan e, as identified by the heavy lines, to limb of the line of subscriber A; the current returning through the substation, over limb S and the talking circuit at the exchange, through contact 108---I05, through the winding of ref y 97 and through the circuits of battery 98.

Vllhile primary movements of shaft 154 cause the closure of contact 137-138, the first secondary movement of the shaft operates to 0 en the said contact and cut bus back mac ine 127 out of circuit with the cal ing subscribers line. While the connector 5' itch is executing switching movements in responserto the transmission, by the calling subscriber, of the impulses representing the third digit of the called subscribersnumber, the calling subscriber hears the busy slgnal. As soon, however, asthc first impulse of the fourth digit is transmitted, the busy signal is no longer heard. This method of operation is found in ractice not to be objectionable. Subscriber r being notified that the called line is busy, replaces his receiver upon. hook lever 6, the lever resuming its normal p0sition as shown in the illustration, arm 6 causing contact to be nmmentarily made between springs 8, 9 and 10 and "thereupon broken. The closing of contact between the said springs connects the two limbs P and S of the line to ground at the substation, which results in'a simultaneous ener ization of relays 91 and 97 of connector switc 1 D. The armatures of the said relays are simultaneously attracted and contact is closed between s rings 92 ahd 96, establishing a path for the lbw of current from ground at second selector switch. C, through contact 75 -72, through the winding of, release relay 65, energizing the said relay, through contact 8,588, through contact between springs 92 and 96, through the winding of release magnet 122 of the connector switch, energizing the said ma net, and to battery 98.

'lhe energization of release relay 65 of second selector switch C'attracts the rela s armature, establishing a path for the ow of current from ground at the first selector switch B, throu 11 contact 31-28, through the winding 0 release relay 4(), throu h Contact 44-47, throu 7 h armature 66 of re ease relay 65, through re ease magnet 67 of the sc cond selector switch, to battery 64. Release relay 40 of the first selector switch attracts its armature to close current from ground, through contact 155*1 56, through the winding of release magnet 154 to battery 22, cansin the energization of the said, magnet. lV lien contact between springs 8, 9 and 10 is broken, relays 91 and 97 of connector switch D are deenergized, and contact 92-96 is opened. Release relays 65 and 40, and 1 lease magnets 67 of the second selector switch and 154 of the first selector switch, are deenergized, which affects the release of second selector switch C and first selec'tor T10 switch B, and the return of their mechanisms to normal, as illustrated. When contact 92-96 is 0 ened, release magnet 122 is deenergized an the connector switch is restored to normal.

In case the line of subscriber F is idle at the time when subscriber A establishes connection therewith, as before described, terminal 151 is connected to battery and the attraction, by relay 99, of its armature 102 to en 12-) gage anvil 103, as before described, fails to energize release magnet 122. Relay 99 becomes dener ized and arms 129, 133,- 139 and 143 are t ereby caused to engage contact points 132, 136, 142 and 146, respeo- 125 tivcly. The closin of contact 136-133 of connector switch establishes ground to terminal 151, rcnderin the line of subscriber F busy, and also establishes a path for the flow of current from ground at connector 130 its switch D, through contact 136-133, through a contact 148-151, through the winding of relay 50 of first selector switch E, to

battery 98, causing the said relay to attract its armatures and cut off the circuits of the first selector switch from the limbs of the line of subscriber F. Subscriber A now depresses key 11,grounding limb P of the line, current flowing from ground at the substation, over the said limb, through relay 91, causing its energization. The resultin attraction of its armature establishes a ath for the flow of current from ground at t e connector switch, through contact 94-93, through contact 100-101, through contact 129-132, through the winding of ringing relay 121, to battery 98. The said relay 121 is energized and attracts its armatures 123 and 124 to include ringing generator 120 in circuit with the line of subscriber F, causing his bell to ring. When subscriber A releases key 11, generator 120 is cut out of circuit. Subscriber F, in res onse to the call, removes his-receiver from 00k 6,. which thereupon closes contact 6-7, establishing a path for the flow of current as follows: from the grounded side of battery 112, through winding 117 of relay 113,the current thereupon joining current from thegrounded side of battery 112, through the lower winding of relay 104, the joint flow proceedin through armature 124 of relay 121, throug contact 143-146, contact 150-153, over limb S of the line of subscriber F, through the transmitter, supplying talking current thereto, through contact 7-6; returning over-limb P of the line, through contact 152-149, through contact 141-139, through armature 123 of relay 121, the current then dividing; a portion flowing through winding 115 of relay 1 13, to the active side of battery112; the other ortion flowinglthrough the u per winding 01 relay 104 to t e active side 0 the said battery.

through contact 106-108, over the talking circuit at the exchangc, as indentified by the heavy line. to limb S of the line of subscriber Afthroi gh the-transmitter at thesubstation,

supplying talking current thereto, through contact 7-0; returning over limb P of the line, ov the other side of the talking 0 t me Windings 115 and 117, disposed upon oppo;

1 through the exchange, through contact 1 109-110, through winding 114 of relay 113, L to the active side of battery 112. W indings 114 and 116 are so proportioned and dis 1: posed upon the core of relay 113 that they neutralize their magnetic eil'ects upon. the core, armature 113 not being attracted. Subscribers A and F are now in conversation. The alternating voice currents, when sub-. scriber F is speaking in his transmitter, are repeated by coils 115 and 117 of difl'erential re ay 113 in circuit with the called subscribers line, to coils 114 and 116, res ectively, in circuit with the line ofthe ca ing subscriber, and by means of the induction coil at the substation, to the receiver of subscriber A. W hen subscriber A is speaking,- the voice currents are repeated from coils 114 and 1.16 to coils 115 and 117 and by means of the induction coil at the substation, to the receiver of subscriber F. During conversation, no impedance is connected to the talkin circuit, other than that of relay 104. It wil be noted that the arrangement of the coils of relay 113 is such that the amount of current flowing through the transmitters of the two subscribers in conversation is inde' pendent of the relative resistances of their respective lines. It will also be noted thatthe neutral condition of the core of difl'erential relay 113 is independent of the relative resistances-of the .lines of connected subscribers, the two windings in circuit with each line independentl neutralizing one another. When the su scribers have fin- ,ished their conversation, they replace their receivers'upon the hooks, which operates to close and then break contact between springs '8, 9 and 10 at "their respective substations. Assuming'that subscriber F does this first, the resulting grounding of the two limbs of his line short circuits winding 117 of relay 113, while current continues flowing through winding in undiminished volume. This imbalances-the neutralizing eflec't'ol" the two 110 windings; armature 118 closes contact 118-- 119, establishing a path for theflow of current from ground at secondselector switch C,'throt h contact 75-72, through the winch ing of re ease relay 65 ofthe second selector 15 switch, energizing said relay, through contact 85-88, through contact 118 -119, through the winding of release magnet 122 energizing it,- a n d to battery 98. 'l he energization of release relay 6,5 of second selector switch C effects the .energization of release ma net 67of the said'switch, as before descri ed, and of release relay 40'of the firet selector switch which, in turn, effects the I cnergization of' release magnet 154 of the 125 said switch.

Referring again to substation F, when l springs 8, 9 and 10 disengage one another. ci-cuit is broken through windings 115 and l 151' i relay 113 and the windings of relay 1w 104, denergizing the relay whose retracted armatures take current from the line of A and windings 114 and 116. Under these circumstances, armature 118 disen ages, anvil 119, opening circuit through re ease magnet 122 of the connector switch, whose de'einergization causes the switch to return to normal. it atso opens circuit throughrelease relay 65 of second selector switch G, which is denergized; it deenergizes release net 67, returning the second selector switc to normal, and also release relay 40 of the first selector switch. The latter relay' deencrgizes release magnet 154 of the first selector switch which thereupon returns to normal. All apparatus, used in establishing the connection, has been returned to normal and, in this case, the act of subscriber A in replacing his receiver is nu atory.

' Assuming that subscriier A replaces his receiver in advance of subscriber F, causing contact between springs 8, 9 and 10 to be closed and the two limbs of his line to be grounded at the substation, winding 116 of relay 113 is short circuited, while current continues flowing in undiminished volu is through winding 114 of the said relay. T he neutralizing eilect of the two windings upon one another is destroyed; the core of relay 113 is magnetized and attracts armature 118 to engage anvil 119. This effects the energization of the release ma nets of the connector switch, the second so ector switch and the first selector switch in the manner described in the case in which subscriber F accomplished the release. When springs 8,

9 and 1G disengage one another, circuit is,

o ened through windings 114 and 116, and t eir unbalancing effect upon the core of relay 113 is destroyed; and assuming that subscriber F has not yet replaced his receiver upon the hook, armature 118 disengages anvil 119 and the release magnets of the various switches are deenergized, causing them to return to normal.

t will be noted that should limbs P and S of both subscribers lines be simultaneously grounded, windings 116 and 117 of relay 113 will be simultaneously short circuited, current continuing to flow through windings 11.4 ,tnd 115. There will thus be a greater unbalancing efiect'upcn the core of relay 11.3 than in the cases in which one subscriber alone accomplished the release operation, joint actions of the subscribers in releasing cooperating with each other. In this case, however, the release of armature 118 01 relay 113 does not occur until ground has been removed from the two limbs of the line of substation 11. We also provide means to enable the calling subscriber, should he desire on account of an error in transmitting a call, or for any other reason during the time he is establishing a connection, to return the a paratus to normal, to accomplish this resu t;

Assuming that the calling subscriber A has operated switch B to connect the switch C, he thereupon replaces liis receiver upon the hook, grounding the two limbs olf his line,

and relays 12 and 16 of switch B are simultaneously energized. The energization of relay 16 closes circuit through electromagnet 18, drawing up armature 19. Current thereupon flows from ground, through contact 14-13, through contact 19-20, through the winding of release magnet 1-54 to battery 22, energilzing magnet 154. When ground is removed. from the two limbs of the line, relays 12 and 16 are deenergized and also magnet 154, which efl'ects the return. of switch B to normal.

Assuming that the calling subscriber has operated switch B and switch C, the latter to connect with the connector switch, and then replaces his receiver, in this case relays 51 and 59 of switch C are simultaneously energized, establishing a path for the flow of current as follows: from ground at switch B, through contact 3128, through the winding of release relay 40, through contact 44-47, through contact 5253, through the winding of release magnet 67 of switch C to battery 64, energizing relay -10 and magnet 67. The energization of relay 40 effects the cnergization of release magnet 154; and when ground is removed from the two limbs of the line at the substation, the resulting opening of contact 5I2--53 results in the deenergization of release magi'iets 67 and 151, and the return of switches and B to normal.

Assuniing that the calling subscriber has operated switches B, (l and l), and desires to return the apparatus to normal, the grounding of the two limbs of the line simultaneously energizes relays 9] and 97 of switch 1), the path for the How of ('ulicnl hereby being established from ground a! switch l. through contact "IS--72, iiwough release rclay 65, contact Si'i SN, through contact 9296 of snitch l), the winding of release magnet 12') to battery 9H. .llvlay 65 of switch (l and magnet 123 of switch D are energized, the drav. ing up of the former preparing the release inechai'iisn'is of switches and B for the return of the av. indies 10 normal, as heretofore described When ground is removed from the limbs of the line at the substation, the dei nergizalion, resulting therefrom, of relays 91 and 97 of switch D, 0

opens contact 92--96, and the release magnets of all three switches are dc nergized and the switches returned to normal. Referring now to Fig. 2, we show a switch mechanism generic to the circuits B, Cand E 125 To avoid repetition of 'comprises inagrnct drawings, we show a single switch, and for fromtooth 18 to engage tooth 18. convenience supply reference characters thereto, corresponding to circuit B. The switch comprises essentially the contact hanks l, and 1, concave in shape as indicated in Fias. 7 and 8, and including each one hundred sets of ontacts arranged in ten super- 1 posed rows of ten contacts each. In front of the banks is placed the shaft43, journaled to the bank supports and carrying wipers 44, and 46. Above the banks, a double ratchet, having horizontal and vertical teeth, is fastened to the shaft. Adapted to engage the Horizontal teeth and lift the shaft and wipers to select contact rows, is the armature-driven pawl 1? controlled by magnet 17; while adapted to engage the vertical teeth and rotate the shaft and wipers to select contacts of the selected rows, is provided armatuire-driven pawl 21 controlled by magnet 21. lhc side switch mechanism 18 with its armaturecontrollcd sprint including teeth 18" and 18 controlling tic movements of pivoted ide switch pawl 18 and consequently of switch-arm 24'fastened to the pawl. For restoring the shaft and side-switch, the 'release magnet 15-1 is provided.

In the operation of the switch, one or more cu rrent i m 1 H1 lscs a re 1 i rst transmitted through primary magnet 17. The first attraction of the mae'nets armature is effective to accomplish three simultaneously occurring results, namely: First, arm 17" lifts arm 154 upward to disengage the pin on double detent d (I; which then moves toward the shaft ratchets, engaging with its upper part a tooth of the horizontal shaft ratchet, and with its lower part-a-tootlr of the vertical ratchet; second, the attraction of the armature eilc ts a tlrust of pawl 17 to engage the upmost tooth of the horizontal ratchet,'lift inc- 1. held in the upper part ofxletent d (1; third, arm 13 so that it frees thepin upon thc'cnd of the arnmture of release magnet 134, otal 18" then moving: a slight. distnnco to the lclt so that arm 18" rests upon the top 4d the said pm. This serves to unlock the side -.\1i!' ii ior its operation, as hereal'tcrdcsrrihcd. Hucressiveimpulsesthrouglr prtwar invent-t 17. after the lir 't, serve only to raise the s alt successive steps upward,

(lhulileilctcnt '1 I/ ciignf iiiu'fwit it curl: thrust,

successive teeth of the ratchet and holding the shaft in the raised position. After the ast impulse {trough magnet 17, a sin'rle im-' pulse is caused to flow through nnurnet 18, as

- described in connection with the circuits.

The said magnet attracts'its arm. i urc, whose associated ratchet is drawn dottmvard.to a posrtlon such that the end of side switch pawl 18 rests'ag'ains t tooth 18. When the magnet is thereafter decn'erfixed, its armature is retracted and the end 0 pawl 18 slips down dealt a step, in which position it By this oted pawl 18, is moved to disengage contact 25 and to engage contact 26.

In Fig. 5 is indicated the manner in which a plurality of circuit-changing arms 24, 28, 32, etc., may be associated with a single side switch pawl 18, suitable sets of insulated contacts being provided for each arm so that each movement of the side switch pawl is effective for a plurality of simultaneous circuit changes. The next step in the opcration of the switch is the sending of one or more impulses through secondary magnet 21. Each is effective to cause the attraction of the magnets armature and a thrust of pawl 21. fastened thereto, which, engaging successive vertical ratchet teeth of the shaft, rotates the shaft and wipers 44, 45 and 46 from contacts to contacts along selected rows. Each time the armature of magnet 21. is attracted, arm 21 engages the armature of side switch magnet 18; and unless the said magnet has become energized a second time, (as described in connection with the circuits, after the first actuation of secondary magnet 21,) arm 21 with the first energization of magnet 21 thrusts the armature of magnet 18 to the right and then releases it, whereby side switch pawl 18 is advanced another step to the leftto engage tooth 18", and arm 24 moved to disengage contaet 26 and to engage contact 27. It is apparent, however, that if magnet 18 becomes energized because the switch 00 wipers are passing over busy contacts, no second step of side switch pawl 18-is possible (such movefnent occurring only when the armature of the magnet is retracted) until magnet 18 becomes denergized, which of course occurs when the. switch wipers engage idle contacts.. WVhen this does occur arni 2]. W111 be in a positionaetrac'ted from the armature of magnet 18,

the armature returns to normal, and the side switch pawl is advanced to engage tooth 18. The restoration of the shaft and side switch mcclumism is accomplished by an impulse of current sent through magnet 1.54. The said magnet, attracting its ar-- 115 mature, bringsarin 154 to the left so that r it engages the pin upon double detent d 6!, while the pin upon. the armature is drawn to a position such that it engages the off-set of arm 18. When, now, magnet 18 is deenergized, its armature is retracted by its associated spring withdrawing, by arm 154,

the. double detent from engagement with the shaft ratchets, and by its pin moves arm 18 and side switeh pawl 18 to their nor- 125.

mal positions, as shown, whereby the side switcharmsare also restored. Upon the withdrawal of double detent dd, the shaft is free to be rotated by spring 43, against whose torsion it was turned, to a position ,130

such that wipers 44, 45 and 46 disengage the bank contacts, when the shaft descends by gravity, assisted by spring 43*, to its normal position. It will be understood that when the switch structure of Fig. 2 is used as a connector (the connector circuit being shown at D of Fig. 1), the arm 21 is omitted.

While, for convenience of illustration, we

have shown a lurality of batteries in Fig. 1, it is to be und rstcod that they may be one and the same battery.

Our invention is not limited in its application to the precise structures shown, and we desire not to be limited thereto, as applications of our invention other than those shown will readily suggest themselves to those skilled in the art.

We claim 1. In a telephone exchange system provided with switching mechanisms at the substations and automatic switches responsive thereto at the exchange for connecting and disconnecting subscribers lines, the combination with a callin subscribers line and a called subscribers hne extending from substations to the exchange and connected for conversation thereat, of an electromagnet adapted to control disconnection of said lines, provided with a core and four energizing windings therefor, two of said windings being in circuit with the calling subscribers line and the other two in circuit with the called subscribers line, a central source of current in circuit with said windings, a disosition of the windings in circuit with each line such that during conversation they neutralize one another with respect to the core of the electromagnet, independently of the windings in circuit with the other line, and

a paratus at each substation under control oi the subscriber, adapted to destroy the neutralizing effect of the windin s in circuit with his line, independently of t e windings in circuit with the other line, to effect actuation of said. electromagnet.

2. In a telephone exchange system provided with switching mechanisms at the substations and automatic switches responsive 5O disconnecting subscribers lines, the combi nation with a callin subscribers line and a called subscribers hne extending from substations to the exchange and connected for conversation thereat, of an electromagnet provided with a core and four energizing windings therefor, two of said windings being in circuit with the calling subscribers line and he other two in circuit with the called subscriber's line, a central source of current in circuit with said windings, a disition of the windings in circuit with each iii? such that during conversation they neutralize one another with respect to the core 66 of the electromagnet, independently of the thereto at the exchange for connecting and windings in circuit with the other line, a pa ratus at each substation under control 0 the subscriber, adapted to destroy the neutralizing effect of the windings in circuit with his line, independently of the windings in circuit with the other line, to effect magnetization of said core, and armature mechanism for said electromagnet controlling disconnection of said lines, adapted to be attracted by the magnetization of said core.

3. In a telephone exchange system provided with switching mechanisms at the substations and automatic switches responsive thereto at the exchange for connectlng and disconnecting subscribers lines, the combination with a callin subscribers line and a called subscribers line extending from substations to the exchange and connected for conversation thereat, of an electromagnet provided with a core and four energizing windings therefor, two of said windings being in circuit with the calling subscribcrs line and the other two in circuit with the called subscriber's line, a central source of current in circuit with said windings, a disposition of the windings in circuit with each line such that during conversation they neutralize one another with respect to the core of the elec: tromagnet, independently of the windings in circuit with the other line, a paratus at each substation under control 0 the subscriber, adapted to destroy the neutralizing effect of the windings in circuit with his line, independently of the windings in circuit with the other line, to effect magnetization of said core, switching mechanism adapted to be actuated by the magnetization of said core and apparatus, responsive to said mechanism, for dlsconnectin said lines.

4. In a te ephone exchange system provided with switching mechanisms at the substations and automatic switches responsive thereto at the exchange for connecting and disconnecting subscribers lines, the combination with two tele hone lines extending from substations to t e exchange, of a central source of current, a repeating device associated with said lines at the exchange, inductivel uniting them for conversation, provided with four windings disposed about a core of. magnetic material, a disposition of said windings such that two are in closed circuit with each line, the windings of each line neutralizing one another with respect to the core during conversation, independently of the windings of the other line, ap aratus at each substation under control 0 the subscriber, adapted to destroy the neutralizing effect of the windings in circuit with his line, independently of the windings in circuit with the other line, to effect magnetization of said core, and apparatus responsive to the magnetization of said core, for disconnecting said lines.

5. In a telephone exchange system provided with switching mechanisms at the substations and automatic switches responsive thereto at the exchange for connecting and disconnecting subscribers lines, the combi- 5 nation with two telephone lines extending from substations to the exchange, of a central source of current, a repeating device associated with said lines at the exchange, inductively uniting them for conversation, provided with four windings disposed about a core of magnetic materlal, a disposition of said windings such that two are in closed circuit with each line, the windings of each line neutralizing one another with respect to the core during conversation, independently of the windings of the other line, ap aratus at each substation under control 0 the subscriber, adapted to destroy the neutralizing effect of the windings in circuit with lllS line,

independently of the windings in circuit with the other line, to efiect magnetization of said core, switching mechanism adapted to be actuated by the magnetization of said core and apparatus responsive to said mechanism, for disconnectin said lines.

6. In a triephone exchange system provided with switching mechanisms at the substations and automatic switches responsive thereto at the exchange for connecting and disconnecting subscribers lines, the combination with two telephone lines extending from substations to the exchange and connected thereat, of a repeating device associated with said lines at the exchange, inductively uniting them for conversation, provided with windings disposed about a core of magnetic material, a central source of current for operating and conversational urposes, supplying current through said lines to the transmitters of the two substations, in quantities inde endent of the comparative resistances of t e lines, the path of said current including windings of said device, a disposition of said windings with respect to the core, such that during conversation their magnetic effects are balanced and the core neutral, a paratus at each substation under contro of the subscriber ada ted, independently of the other subscriher, to unbalance the magnetic effects of said windings to magnetize said core, armature mechanism associated with said device, actuated by magnetization of said core, and apparatus responsive to said mechanism, for disconnectin said lines.

7. In a te ephone exchange system provided with switching mechanisms at the substations and automatic switches responsive thereto at the exchange for connectlng and disconnecting subscribers lines, the combination with two telephone lines extending from substations to t e exchange and connected thereat, of a repeating device associated with said lines at the exchange, in- 65 ductively uniting them for conversation,

provided with windings disposed about a core of magnetic material, a central source of current for o crating and conversational urposes, supp ying current through said ines to the transmitters of the two substations, in quantities inde endent of the com-, parative resistances of t e lines, the path of said current including windin s of said de vice, a dis osition of said win ings with respect to t e core, such that during conversation their magnetic effects are balanced and the core neutral, a paratus at each substation under contro of the subscriber ada ted, independently of the other subscri er, to unbalance the magnetic effects of said windings to magnetize said core, and apparatus res onsive to magnetization of said core, for isconnecting said lines.

8. In a telephone exchange system provided with switching mechanisms at the substations and automatic switches responsive I thereto at the exchange for connecting and during conversation, a paratus at each substation, under contro of the subscriber, adapted to independently destroy neutrality of and magnetize said core, and ap aratus responsive to such magnetization, or disconnecting said lines.

9. In a telephone exchange system provided with switching mechanisms at the substations and automatic switches responsive thereto at the exchange for connectingand disconnecting subscribers lines, the combination with a calling subscn'bers line and a called subscribers line extending from substations to the exchange, of an electromagnet at the exchange in circuit with the line, and ada ted to be energized upon the response, of t 1e called subscriber, switching mechanism responsive to the energization of said electromagnet, and a repeating coil relay for connecting said lines for conversation switched into operative relation with the calling line by said mechanism.

10. In a telephone exchange system provided with switching mechanisms at the sub stations and automatic switches responsive thereto at the exchange for connecting and disconnecting subscribers lines, the combination with two telephone lines extending from substations to the exchange and connected for conversation thereat, of an electromagnet associated with said lines at the exchange,provided with four windings disposed about a core of magnetic material, two of said windings being in circuit with each line, a central source of current supplying talking curren to the transmitters of the substations, in quantities independent of the comparative resistaanrcs of the lines. the path for each subsla lion including the two windings in circuit with its line, a disposition of said winding-s with respect to the core, such that during conversation those in circuit with each line balance one another to maintain the core neutral, apparatus at each substation under control of the subscriber, adapted to destroy the neutralizing; effect. of the windings in circuit with his line, independently of the windings in circuit with the other line, to effect magnetization of the core, and apparatus responsive to such magnetization, adapted to disconnect said lines.

11. in a telephone exchange system provided with switchingmechanisms at the substations and automatic switches responsive thereto at the cxchange for connecting and disconnecting subscribers lines, the combi nation with two telephone lines extending from substations to the exchange and connected .lor conversation thereat, of an electronmgnei associated with said lines at the exchange, provided with tour windings disposed about a core of magnetic material, two of said windings being in circuit with each. line, a. central source of current supplying talkin current to the transmitters of the substations, in quantities 'imlcnendent of the comparative resistances of the lines, the path for each substation including the two windings in circuit with its line, a disposition of said windings with respect to the core, such that during conversation those in cii cuit with each line balance one another to ina ntain the core neutral, apparatus at each substation destroy the neutralizing eil'ecl oi the windings in circuit with his line. independently of the windings in circuit with the other line, to effect magnetization oi" the core, switching, mechanism adapted to be actuated by the magnetization of said core, and apparatus responsive to said mechanism for disconnecting said lines.

12. vln a telephone exchange system, the combination with two telephone lines extendinn from substations to the exchange, of an electroniagnet provided with a core and four windings therefor, two ol' said windings being i in circuit with the line of each subscriber, a. central source of current. in circuit with said windings, a disposition of the windings in circuit with each line such that whcn equal current is flowingin them, neutralize one another with respect to the core, indw pendently of the other windings, and apparatus at each substation under control of the subscriber. adapted to effect a prcpomltn-ance of current in one ofthe windings in circuit with his line to magnetize said core independently of the windings in circuit wit h the other line.

13. A telephone circuit with resistances therein; a repeating coil havin." equal and opposite windings of equal it istanccs: a battery bridged between said windings and connected. to ground; a controlling circuit, controlled by the called party; a circuit controlling mechanism in the controlling circuit whereby the resistances are cut out oi the telephone circuit and the repeating coil is substituted therefor; an armature adjacent to the coil a restoring. magnet circuit containing said armature, and a restoring magnet; a restoring magnet armature o )eratively connected with the circuit controlling mechanism to restore the apparatus employed to normal position; and electromagnetic means whereby an unbalancing of the repeating coil causes the repeating coil armature to complete the restoring magnet circuit thereby causing the restoring n'lagnet armature to restore the circuit controlling mechanism and hence to cut out the repeating coil by restoring all the apparatus employed to normal position. i

14. An automatic telephone exchange system including a pair of connected telephone lines, a plurality of selective switches associated therewith through which the conversational circuit extends, a ditlcrential repeal ing relay having windings in circuit wit li said lines, release magnets one to? each of said switches, and means at a substation l'or controlling said relax' to operate said release magnets at the will of the subscriber.

15. An automatic. telephone excha nee s vstem including a calling line. a called line. a connector adapted for operation by currents 1 over the calling line to connect dire tly with under control of the subscriber. adapted to the called line, a normally open link-circuit for said connector, a dill'crcniial repeating relayhaving windings l'or induct i\cl unit hay said lines for conversation, a rcla operatin: after connection math-with the called line to render said normally opt-n circuit conductively continuous whereby said dill'crential relay is rendered cllect ive to unite said lines, and means at the substation ot' a line for temporarily ell ecling a prcpondcrating llow of current in a winding; of said difi'crential relay to restore said connector to normal.

16. in an automatic telephone exchange system. a calling subscribens line, switching mechanism at the substation, a called subscribcr's line, selective switches at {die exchange of a plurality of classes arranged for successive operation responsive to said mechanism in completing a. connection between said lines, a ditl'crcntial repeating relay at the exchange with windings adapted for connection to said lines, a central source ol current connected to said windings to supply current there through to said lines for conversational Purposes in quantities independent of the relative resistances of the lines, and means at lllt) derating flow of current in e winding of said relay. J 17. A telephone circuit with resistances therein; a repeating coil; a controlling cir- 5 (hit controlled by called party; a circuit controlling mechanism in the controlling circuit whereby the resistances are cut out of the ttlLl ilmlle circuit; and the repeating coil is subsltituted therefor, and a talking circuit it resu ts.

15. A telephone circuit with resistances sin-rein. a repeating 0011, a controlling circuit l ontrolled by the called party, a circuit conuolhng mechanism in the controlling circuit whereby the resistances are cut out of 'the telephone circuit and the re eating coil is substituted therefor and a talking circuit results, a restoring relay circuit, on armature in said circuit, and electromagnetic means whereby the apparatus employed may be restored to normal position.

In witness whereof, we hereunto subscribe our names this 19th (iii of June, A. D., 1905. ALFR D H. DYSON.

v FRANCIS W. DUNBAB.

Witnesses:

A. B. MCDQNOUGH, CHAS. JUSBY. 

